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Hammering as each zone starts up

As each zone starts up, there is a hammering in the house lines - sounds like water is being turned off/turned on rapidly (like the washing machine does). Also, the vacuum breaker spouts water each time it hammers, then shuts off. Some zone start-ups are more pronounced than others.
Any help?
Thanks.

You have to have a plumber install a Hammer valve in the house where the water comes in .And if you want to go one further install a BackFlow Preventer before your sprinkler main valve (gate or Ball valve)

If the hammer valve does not seem to fix the problem. More than likely the contractor who installed your system overloaded the zones (to many GPM per zone) Industry standard is water traveling 5 feet per second. Any time you demand more water than what the pipe is sized for, you get water traveling faster that 5 fps. Any thing over 7fps and high water psi will cause hammer when the zone turns on and off.

The way you can prove this is the cause. Have a couple of kids stand on 30% of the heads on one zone so they cannot come up. Have someone else turn on that zone. Listen to the pipes they should not hammer anymore since you are not demanding more than what your water pipes are sized for.

The fix: most controllers have a "jumper" in them that you can allow a 5 second delay between zones turning on and off. This will not allow 2 zones to be on while move from one to another.